Caption not displaying for linked image

Hi,
I have this code in my page in a custom HTML block:
<span class="samaritan-circle"><a href="/wp-content/uploads/2020/06/The_Good_Samaritan_by_Vincent_Willem_van_Gogh.jpg"> &nbsp; </a></span>

The span has a background image. When clicked the image comes up just fine with Featherlight, but I need the caption to show also. There is a caption in the media library, but it doesn’t show up here. Is there additional code I can add to have the caption show?

Thank you!